/*
Copyright 2021 The Kubernetes Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package io.kubernetes.client.openapi;

import java.io.IOException;
import okhttp3.*;
import okio.Buffer;
import okio.BufferedSink;
import okio.GzipSink;
import okio.Okio;

/**
 * Encodes request bodies using gzip.
 *
 * <p>Taken from https://github.com/square/okhttp/issues/350
 */
class GzipRequestInterceptor implements Interceptor {
  @Override
  public Response intercept(Chain chain) throws IOException {
    Request originalRequest = chain.request();
    if (originalRequest.body() == null || originalRequest.header("Content-Encoding") != null) {
      return chain.proceed(originalRequest);
    }

    Request compressedRequest =
        originalRequest
            .newBuilder()
            .header("Content-Encoding", "gzip")
            .method(originalRequest.method(), forceContentLength(gzip(originalRequest.body())))
            .build();
    return chain.proceed(compressedRequest);
  }

  private RequestBody forceContentLength(final RequestBody requestBody) throws IOException {
    final Buffer buffer = new Buffer();
    requestBody.writeTo(buffer);
    return new RequestBody() {
      @Override
      public MediaType contentType() {
        return requestBody.contentType();
      }

      @Override
      public long contentLength() {
        return buffer.size();
      }

      @Override
      public void writeTo(BufferedSink sink) throws IOException {
        sink.write(buffer.snapshot());
      }
    };
  }

  private RequestBody gzip(final RequestBody body) {
    return new RequestBody() {
      @Override
      public MediaType contentType() {
        return body.contentType();
      }

      @Override
      public long contentLength() {
        return -1; // We don't know the compressed length in advance!
      }

      @Override
      public void writeTo(BufferedSink sink) throws IOException {
        BufferedSink gzipSink = Okio.buffer(new GzipSink(sink));
        body.writeTo(gzipSink);
        gzipSink.close();
      }
    };
  }
}
